<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script>
        'use strict';
        var msg = `
        sf
        dsf
        sksd
        dsfs
        `
        var arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
        console.log(msg);
        console.log(msg.length);
        console.log(msg.substring(0, 2));

        var person = { name: 'zs', age: 18 };

        // arr.forEach(function (item, index, array) {
        //     console.log(index, item, array);
        // });

        for (var item in arr) {
            console.log(item);
        }
 
    </script>
</head>
<body>
    <h1>字符串</h1>
    <h2>字符串的不可变性</h2>

</body>
</html>